1. Field of the Invention
The present invention relates to light guide plates used in backlight modules of liquid crystal display devices and, particularly, to a light guide plate having high brightness and uniformity of light emission and to a backlight module adopting the same.
2. Description of Related Art
Liquid crystal display devices have many excellent performance characteristics, such as large-scale information display ability, easy colorization, low power consumption, long life, no pollution associated therewith, and so on. Therefore, liquid crystal display devices are widely used. A typical liquid crystal display device generally includes a backlight module. The backlight module is used to convert linear light sources or point light sources, such as cold cathode ray tubes or light emitting diodes, respectively, into area light sources with high uniformity and brightness.
Referring to FIGS. 6 and 7, a conventional backlight module 10 includes a number of LEDs 12 used as light sources and a light guide plate 13 adjacent to the light sources 12. The light guide plate 13 includes a light incident surface 131 adjacent to the light sources 12, a light emitting surface 132 adjoining the light incident surface 131, and a bottom surface 133 opposite to the light emitting surface 132. In use, incident light beams are emitted from the light sources 12 and are transmitted into light guide plate 13. The light guide plate 13 is used to direct the travel of the incident light beams therein and to ensure that most of the incident light beams can be emitted from the light emitting surface 132 of the light guide plate 13.
However, each LED 12 generally has a limited range of light emission angles. As a result, a number of dark regions 15 tend to be formed in areas of the light guide plate 13, between every two adjacent LEDs 12. A number of bright regions 16, conversely, tend to be formed in areas of the light guiding plate 13, corresponding to each LED 12. Thus, the backlight module 10 can have non-uniform brightness.
What is needed, therefore, is a light guide plate having high brightness and uniformity of light emission, and a backlight module adopting the improved light guide plate. What is also needed is a light guide plate that offers the ability to produce selected lighting characteristics within different regions of the light emission surface thereof.